The six 35mm SLR mounts you can easily adapt to Canon EOS with simple ring adapters (no optical elements) that are readily available are:
- Leica R
- Nikon F
- Pentax K
- Olympus OM
The all have mounts deeper than Canon EF. (See also: Can I use lens brand X on interchangeable lens camera brand Y?). All film-era medium format lenses are probably also adaptable, but some mounts are easier to find adapters for than others.
As you've noted, there are a number of shallower mounts that can be adapted to Canon EF, but would require an optical element in the adapter to act as a teleconverter, to achieve focus to infinity, and like any tc, it will reduce the maximum aperture and add to the focal length of the lens; and cheap ones will probably compromise image quality to some degree. The only exception to this (without modifying the lens mount) I can think of is the Minolta Rokkor 58/1.2, for which you can purchase a Leitax lens mount replacement kit.
Keep in mind it's not just autofocus you lose, but also aperture control from the camera body and lens EXIF information (i.e., any electronic communication with the lens). You can only shoot in M and Av modes, and you'll be using stop-down metering, not wide-open metering. Also, if you get a really fast lens (f/1.4 or wider), DoF rendering on the focus screen may not be accurate unless you have one of Canon's high-precision matte focusing screens or a split-circle focus screen installed, and most Canon bodies don't allow for swapping focus screens.